9.04 Power Management

I've just installed Ubuntu 9.04 onto both my desktop and my Toshiba L300. The laptop freezes and has to be switched off by brutal means when the power management puts the machine to sleep. I have set that option to "Never" to avoid the problem.

Is there something I can do about that?

The desktop machine often freezes when I do a normal shut down and leaves me having to switch off the power to recover.